Lactate reduces liver and pancreatic injury in Toll-like receptor- and inflammasome-mediated inflammation via GPR81-mediated suppression of innate immunity

Gastroenterology. 2014 Jun;146(7):1763-74. doi: 10.1053/j.gastro.2014.03.014. Epub 2014 Mar 20.

Abstract

Background & aims: The NACHT, LRR, and pyrin domain-containing protein 3 (NLRP3) inflammasome induces inflammation in response to organ injury, but little is known about its regulation. Toll-like receptors (TLRs) provide the first signal required for activation of the inflammasome and stimulate aerobic glycolysis to generate lactate. We examined whether lactate and the lactate receptor, Gi-protein-coupled receptor 81 (GPR81), regulate TLR induction of signal 1 and limit inflammasome activation and organ injury.

Methods: Primary mouse macrophages and human monocytes were incubated with TLR4 agonists and lactate and assayed for levels of pro-interleukin (IL)1β, NLRP3, and caspase-1 (CASP1); release of IL1β; and activation of nuclear factor-κB (NF-κB) and caspase-1. Small interfering RNAs were used to reduce levels of GPR81 and arrestin β-2 (ARRB2), and an NF-κB luciferase reporter transgene was transfected in RAW 264.7 cells. Cell lysates were analyzed by immunoprecipitation with an antibody against GPR81. Acute hepatitis was induced in C56BL/6N mice by administration of lipopolysaccharide and D-galactosamine. Acute pancreatitis was induced by administration of lipopolysaccharide and cerulein. Some mice were given intraperitoneal injections of sodium lactate or small interfering RNA against Gpr81. Activation of NF-κB in tissue macrophages was assessed in mice that expressed a reporter transgene.

Results: In macrophages and monocytes, increasing concentrations of lactate reduced TLR4-mediated induction of Il1B, Nlrp3, and Casp1; activation of NF-κB; release of IL1β; and cleavage of CASP1. GPR81 and ARRB2 physically interacted and were required for these effects. The administration of lactate reduced inflammation and organ injury in mice with immune hepatitis; this reduction required Gpr81 dependence in vivo. Lactate also prevented activation of NF-κB in macrophages of mice, and, when given after injury, reduced the severity of acute pancreatitis and acute liver injury.

Conclusions: Lactate negatively regulates TLR induction of the NLRP3 inflammasome and production of IL1β, via ARRB2 and GPR81. Lactate could be a promising immunomodulatory therapy for patients with acute organ injury.

Keywords: Immune Regulation; Innate Immune Response; Mouse Model; Pancreas.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / administration & dosage
  • Anti-Inflammatory Agents / pharmacology*
  • Arrestins / metabolism
  • Carrier Proteins / metabolism
  • Cell Line
  • Ceruletide
  • Chemical and Drug Induced Liver Injury / etiology
  • Chemical and Drug Induced Liver Injury / genetics
  • Chemical and Drug Induced Liver Injury / immunology
  • Chemical and Drug Induced Liver Injury / metabolism
  • Chemical and Drug Induced Liver Injury / pathology
  • Chemical and Drug Induced Liver Injury / prevention & control*
  • Cytoprotection
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Down-Regulation
  • Galactosamine
  • Humans
  • Immunity, Innate / drug effects*
  • Inflammasomes / drug effects*
  • Inflammasomes / immunology
  • Inflammasomes / metabolism
  • Injections, Intraperitoneal
  • Interleukin-1beta / metabolism
  • Lipopolysaccharides
  • Liver / drug effects*
  • Liver / immunology
  • Liver / metabolism
  • Liver / pathology
  • Macrophages / drug effects
  • Macrophages / immunology
  • Macrophages / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Monocytes / drug effects
  • Monocytes / immunology
  • Monocytes / metabolism
  • NF-kappa B / metabolism
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Pancreas / drug effects*
  • Pancreas / immunology
  • Pancreas / metabolism
  • Pancreas / pathology
  • Pancreatitis / chemically induced
  • Pancreatitis / genetics
  • Pancreatitis / immunology
  • Pancreatitis / metabolism
  • Pancreatitis / pathology
  • Pancreatitis / prevention & control*
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism*
  • Signal Transduction / drug effects
  • Sodium Lactate / administration & dosage
  • Sodium Lactate / pharmacology*
  • Toll-Like Receptor 4 / drug effects
  • Toll-Like Receptor 4 / metabolism
  • Toll-Like Receptors / drug effects*
  • Toll-Like Receptors / metabolism
  • Transfection
  • beta-Arrestin 2
  • beta-Arrestins

Substances

  • ARRB2 protein, human
  • Anti-Inflammatory Agents
  • Arrb2 protein, mouse
  • Arrestins
  • Carrier Proteins
  • GPR81 protein, human
  • Hcar1 protein, mouse
  • Inflammasomes
  • Interleukin-1beta
  • Lipopolysaccharides
  • NF-kappa B
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • Nlrp3 protein, mouse
  • RNA, Small Interfering
  • Receptors, G-Protein-Coupled
  • TLR4 protein, human
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • beta-Arrestin 2
  • beta-Arrestins
  • Galactosamine
  • Ceruletide
  • Sodium Lactate